[SIPForum-techwg] Question re Application Server

[Chris Sibley]

Hi Hadriel,

Thanks for the feedback. Comments inline below.

Thanks,

--Chris

> -----Original Message-----
> From: Hadriel Kaplan [mailto:HKaplan at acmepacket.com]
> Sent: Friday, September 08, 2006 2:10 PM
> To: Chris Sibley; 'Paul Kyzivat'; 'SIP Forum Tech WG'
> Subject: RE: [SIPForum-techwg] Question re Application Server
> 
> I think the problem with going down this road is the same problem we
had
> several months ago, where we go beyond the scope of the doc to cover
what
> an
> SP does inside their network, and an end-to-end perspective for one
> particular service.  This is an interface spec/profile between an SP
and
> Ent, and no more.  What the SP does inside their network, whether it
be on
> one App Server, or on 14 proxies, or just with one PSTN-GW integrated,
> doesn't really matter for this doc's purpose.
> 
> For example, now you've got a section on Calls originating from
another
> Enterprise.  What about calls originating from a consumer/subscriber?
Or
> calls originating from another service provider?  Or calls originating
> from
> another voip protocol?  Down the slope we go.
> 

I agree that we need to limit scope, but the points that Paul brought up
are hard to ignore. If we don't at least cover the
Enterprise<-->Enterprise scenario then I think we would have a serious
functionality deficiency given the way the text currently reads (i.e.
the SP couldn't route calls between two Enterprises that it services
without being a B2BUA.) 

I'm not sure what you meant by consumer/subscriber. Would this class of
user really be fundamentally different enough to warrant different URI
formatting conventions? AFA another Service Provider goes, I would think
that the same rules that apply to Enterprise<-->Enterprise calls would
probably also apply there (but it would be out-of-scope for this spec,
really). IMO, calls originated from another VoIP protocol would also be
out-of-scope..

> But I also agree with Paul/Francois that we should not break an
end-to-end
> model.  So... can't we just say that PSTN-originated calls will look
like
> XYZ as defined, but that the enterprise PBX should expect that the
To/From
> can be different, for example if calls didn't come from the PSTN?
> 
> 
> Other comments:
> 
> Section 13.2.3 example is not a start line with a request-URI format.
> It should be:
> INVITE sip:+16789901234 at acmerockets.com;user=phone SIP/2.0
> 

Good catch. I will fix that..

> Out of curiosity, why is the display-name of the From example in
13.1.1
> set
> to the destination Enterprise's name?  I recommend you don't have a
> display-name at all, or we get hampered with what should be in it.
> 

The name is just an example name, but you are right, it should probably
be changed to something different than what we use for the 'To:' field
example in order to avoid confusion. I don't think we should remove the
name altogether, though. IMO, if a name is available (whether through
population by the originating Enterprise's PBX, a CNAM lookup by the
Application Server, etc.) then the SP should deliver it..

> Editorial: section 13.1.3, last sentence needs to reference 13.1.2
now,
> not
> 13.2.  

Another good catch - I will correct that..


>Also sections 13.2.2 should be 13.2.1, and the To part should be
> labeled section 13.2.2.
> 

Thank you Microsoft Word Autocorrect. :) The numbering is actually
correct on the "master" file but got messed up somehow when I pulled the
snippet out to send to everyone for review. I will make sure the
finished product doesn't have the same problem.

> Section 13.2.2: This is a nit, but I think Paul/Francois' point was
that
> the
> App Server should not be mandated to "populate" the To or From fields
at
> all, it should really act as a Proxy.  (unless of course it is
providing
> an
> anonymization service, in which case it does the same as section
13.1.1)
> 

Perhaps we should say the following instead:

The SIP Application Server and/or Service Provider SIP Proxy Server MUST
NOT modify the contents of the 'To:' field when forwarding the request
to the Enterprise's SIP Proxy Server.

> -hadriel
> 
> 
> > -----Original Message-----
> > From: techwg-bounces at sipforum.org
[mailto:techwg-bounces at sipforum.org]
> On
> > Behalf Of Chris Sibley
> > Sent: Friday, September 08, 2006 10:45 AM
> > To: Paul Kyzivat; SIP Forum Tech WG
> > Subject: Re: [SIPForum-techwg] Question re Application Server
> >
> > Team,
> >
> > Attached is the first pass of my edits for Section 13 to address the
> > issue that Paul brought up. Please take a look and let me know what
you
> > think. In case you are not aware, I believe we are scheduled to
announce
> > the availability of this recommendation on Tuesday so I would
appreciate
> > your feedback as soon as you can.
> >
> > Thanks!
> >
> > --Chris
> >
> >
> > > -----Original Message-----
> > > From: techwg-bounces at sipforum.org
[mailto:techwg-bounces at sipforum.org]
> > On
> > > Behalf Of Chris Sibley
> > > Sent: Thursday, September 07, 2006 11:21 AM
> > > To: Paul Kyzivat; SIP Forum Tech WG
> > > Subject: Re: [SIPForum-techwg] Question re Application Server
> > >
> > > Hi Paul,
> > >
> > > Firstly, my apologies for taking so long to respond. I have been
on
> > > vacation and it's taken a while to dig myself out.
> > >
> > > Secondly, thanks for your very astute comments! You are quite
right
> > > that, given the current wording, calls between Enterprises
(handled by
> > > the SP) would require a B2BUA. When this text was written, we were
> > > (only) contemplating calls that ORIGINATED from the PSTN and were
> > > destined to an Enterprise. So, in this scenario, since the headers
are
> > > actually being created for the first time the text would be
correct.
> > >
> > > However, as you pointed out, there is certainly significant value
in
> > the
> > > SP handling calls BETWEEN Enterprises. That said, I think we need
to
> > > clarify Section 13 to define rules for calls that originate from
the
> > > PSTN (current wording) as well as calls that originate from
another
> > > Enterprise (and handled by the SP, of course).
> > >
> > > What do you think? If everyone agrees I can put together something
> > today
> > > / tonight and send it out for your review..
> > >
> > > Thanks,
> > >
> > > --Chris
> > >
> > >
> > > > -----Original Message-----
> > > > From: techwg-bounces at sipforum.org
> > [mailto:techwg-bounces at sipforum.org]
> > > On
> > > > Behalf Of Paul Kyzivat
> > > > Sent: Friday, September 01, 2006 1:41 PM
> > > > To: SIP Forum Tech WG
> > > > Subject: [SIPForum-techwg] Question re Application Server
> > > >
> > > > I am trying to understand the nuances of draft 5, and there is
> > > something
> > > > I am unsure of: Is the Application Server required to act as a
> > B2BUA,
> > > or
> > > > is it permitted to act as a proxy? There is no mention of B2BUAs
in
> > > the
> > > > document, but I think it may be implied.
> > > >
> > > > In particular, suppose we have one service provider servicing
two
> > > > enterprises: acme.com and bozo.com.
> > > >
> > > > Acme has a phone number +12125551234, and Bozo has +14085556789.
> > Then
> > > > Acme calls Bozo. According to the spec, the call from Acme is
> > > addressed
> > > > as:
> > > >
> > > > 	INVITE sip:+14085556789 at serviceprovider.net;user=phone
SIP/2.0
> > > > 	To: <sip:+14085556789 at serviceprovider.net;user=phone>
> > > > 	From: <sip:+12125551234 at acme.com;user=phone>
> > > >
> > > > But then the instructions for service provider addressing say
that
> > > when
> > > > this is sent to Bozo that it should be addressed as:
> > > >
> > > > 	INVITE sip:+14085556789 at bozo.com;user=phone SIP/2.0
> > > > 	To: <sip:+14085556789 at bozo.com;user=phone>
> > > > 	From: <sip:+12125551234 at serviceprovider.net;user=phone>
> > > >
> > > > To change the To and From fields in this way requires that the
> > > > Application Server be a B2BUA. If this is routed using proxy
> > routing,
> > > > then the message going to Bozo would perhaps look like:
> > > >
> > > > 	INVITE sip:+14085556789 at bozo.com;user=phone SIP/2.0
> > > > 	To: <sip:+14085556789 at serviceprovider.net;user=phone>
> > > > 	From: <sip:+12125551234 at acme.com;user=phone>
> > > >
> > > > So, is it a requirement to have a B2BUA in the path, or is proxy
> > > routing
> > > > ok?
> > > >
> > > > 	Thanks,
> > > > 	Paul
> > > > _______________________________________________
> > > > techwg mailing list
> > > > Send mail to: techwg at sipforum.org
> > > > Unsubscribe or edit options at:
> > > > http://sipforum.org/mailman/listinfo/techwg
> > >
> > >
> > >
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